: Many epidemiological studies have shown a correlation between intrauterine growth retardation and the onset of insulin resistance, NIDDM, hypertension, hyperlipidemia and cardiovascular diseases. This association has been explained by a concept termed re-programming, whereby intrauterine exposure to insufficient nutrient supply during critical periods of fetal life would permanently affect the development and function of the endocrine system, leading to metabolic changes, including insulin resistance. Knowledge of the mechanisms of re-programming might allow new strategies for early prevention of long-term metabolic disturbances like diabetes. This project will examine the relationship between intrauterine growth retardation (IUGR), insulin resistance and fetal growth, using fetal hepatic growth in rats as a model. This study will serve to characterize the mechanisms involved in the signal transdution pathways and the cell cycle that promote growth in the liver of IUGR rats, thereby demonstrating the effects of maternal fasting on hepatic growth. With this knowledge, the concept of re-programming may be better understood to help explain fetal origins of adult disease.